On 08/17/2010 09:40 AM, Michael Tokarev wrote:
fsync() being slow is orthogonal to my point. I don't see why we
need to do an fsync() on *every* write. It should only be necessary
when a guest injects an actual barrier.
We don't do sync on every write, but O_SYNC implies that.
And apparently it is what happening behind the scenes in
ext4 O_SYNC case.
I think the real issue is we're mixing host configuration with guest
visible state.
With O_SYNC, we're causing cache=writethrough to do writethrough through
two layers of the storage heirarchy. I don't think that's necessary or
desirable though.
Regards,
Anthony Liguori
But ok....
/mjt
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